Shock absorber having a piston permanently attached to its piston rod

ABSTRACT

A shock absorber valve for a hydraulic telescoping strut shock absorber, has, running through a valve body, passages whose respective outlet-side openings are covered by ring-shaped valve discs, whereby the valve discs and the valve body are fastened and axially braced in line. A fully-automated assembly with short cycle times using the dry process can be made possible, whereby a valve closing force independent of tolerances is achieved by using a method which generates as few chips from cutting and machining as possible. To achieve this, the valve discs and the valve body are fastened and prestressed onto a cylindrical component using a fastening element, which fastening element is non-detachably fixed to the cylindrical component.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a shock absorber valve for ahydraulic telescoping shock absorber, in which, running through a valvebody, there are passages whose respective output-side openings arecovered by ring-shaped valve discs, whereby the valve discs and thevalve body are fastened and axially braced in line on a journal.

2. Background Information

Such a valve for hydraulic telescoping strut shock absorbers isdisclosed in German Patent No. 38 20 307, in which the valve is locatedin the piston of the telescoping strut shock absorber, whereby the leafsprings for the pressurization of the passages are actuated by a coilspring. The leaf springs, the valve body and the coil spring are therebyaxially threaded onto a journal of the piston rod, and are braced andfastened by a piston nut.

It is essentially always a complex, expensive and time-consumingoperation to manufacture the threaded portion of the journal. Anadditional disadvantage is that a threading process basically entails anotching action which significantly reduces the tensile strength of thejournal. Measures must also generally be taken to secure the piston nut.

OBJECT OF THE INVENTION

The object of the present invention is to create a valve for a shockabsorber which can be assembled and secured fully automatically with ashort cycle time, and which also essentially eliminates thedisadvantages of the valves utilized in the past.

SUMMARY OF THE INVENTION

The present invention teaches that this object can preferably beaccomplished by fastening at least some of the valve discs and the valvebody on the journal by means of an essentially nondetachable positivefit, which may alternatively be termed a "deformation fit" or a "forcefit".

All the disadvantages of a threaded connection used in the past canessentially be eliminated by the nondetachable positive fit. Likewise,there are essentially no adjustment problems for the valve dampingforce, since the effect of friction inside the above-referenced threadedconnection is preferably essentially eliminated.

To prevent the formation of chips from cutting or machining processes,one advantageous feature of the present invention is that the fasteningis preferably a positive fit and/or a weld joint. Such a valveconstruction can preferably be installed essentially without problems ina piston, and also as a bottom valve in the shock absorber.

The present invention also teaches that the positive fit is preferablyformed by the journal. According to an additional advantageous featureof the present invention, the journal preferably has a blind hole, sothat a ring wall is formed which ring wall preferably has an overhang inrelation to the valve discs and valve body threaded onto it, whereby theoverhang can preferably form the positive fit by means of a bead. Thereis also advantageously an overlap between the blind hole and the valvebody. Thus, a bearing force can be achieved which causes an additionalaxial force, but also essentially eliminates the play which can bepresent, under some circumstances, between the valve body and thejournal.

So that the valve discs cannot be damped uncontrollably, there ispreferably at least one supporting ring for the valve discs locatedinside the row of components axially braced in line. In an additionaladvantageous embodiment of the present invention, the supporting ringpreferably has a rolling contour, so that the damping occurs accordingto a desired behavior. For example, in one advantageous configuration,the rolling contour can be formed by two connected, essentially conicalsurfaces. The result is a damping force characteristic which ispreferably graduated.

To reduce the manufacturing costs for the valve body, in the function ofa piston valve, the piston ring is fastened to the valve body preferablywithout undercutting. The use of a sintered valve body can also resultin major advantages in terms the sintering dies. For a valve body madeof sheet metal, the deforming expense can also essentially be reduced.To increase the allowable axial load of the piston ring, one supportingring preferably has a fastening surface for the piston ring.

An additional advantageous feature of the present invention is that thesupporting ring, with its fastening surface, can preferably be partlysupported on the end face of the valve body. The piston ring is therebypreferably excluded from the row of axially braced components of thevalve in terms of tolerances.

In an additional configuration, the valve discs facing the piston rodand the valve body are preferably fixed axially.

From a manufacturing point of view, an advantage of the presentinvention when incorporated on the piston of a shock absorber, is thatthe cylindrical component is preferably a component of the piston rod.The piston rod can thereby be provided with a journal in the vicinity ofits piston, so that this journal can be used for the axial threading ofthe valve discs and valve body.

One characterizing feature of the present invention is that thecylindrical component is preferably provided with a hole, in which acylindrical component provided with the valve discs is fastened.

To preferably achieve a positive fit by a non-cutting forming operation,in one embodiment of the present invention, the cylindrical component ispreferably surrounded by the fastening element, and the cylindricalcomponent is expanded from inside to outside.

According to an additional characterizing feature of the invention, theexpansion of the cylindrical component is preferably accomplished bymeans of an expander element located in a hole of the cylindricalcomponent. A sphere can be advantageously used as the expander element.

To further improve the positive fit, preferably between the fasteningelement and the cylindrical component, the cylindrical component and/orthe fastening element is/are provided, preferably on the surfaces facingone another, with at least one projection and/or one recess. Theprojection and/or the recess preferably run in an annular fashion overthe entire circumference.

In an additional configuration, the fastening element is preferably madeof light metal or a light metal alloy, and the fastening element ispreferably shrink-fitted, onto the cylindrical component in anessentially contactless manner by electrically pulsed magnetic fields.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are schematically illustrated inthe accompanying drawings.

FIG. 1 shows a shock absorber, partly in cross section and partly in aplan view;

FIGS. 2 and 3 show a piston of a shock absorber in cross section;

FIGS. 2a and 3a show substantially the same views as FIGS. 2 and 3, butshow additional components;

FIGS. 4-7 illustrate various pistons of a shock absorber in crosssection; p FIG. 4a shows an additional embodiment of a piston similar tothat shown in FIG. 4.

FIGS. 5a, 6a, and 7a show substantially the same views as FIGS. 5-7, butshow additional components;

FIGS. 8a-8d illustrate the sequence of assembly of one realization of apiston;

FIG. 9 illustrates a bottom valve of a shock absorber, partly in crosssection and partly in a plan view;

FIG. 9a shows substantially the same view as FIG. 9, but showsadditional components; and

FIGS. 10 and 11 show a typical shock absorber in which the embodimentsof the present invention could be incorporated.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a shock absorber which preferably includes anexternal tube 4, a piston 3 fastened to a piston rod 2, and thefastening devices 5 which are preferably fastened to the piston rod 2and to the external tube 4.

The piston 3 illustrated in FIG. 2 essentially includes a valve body 7,which valve body 7 is preferably provided with passages 8a/8b, one foreach direction of flow. The passages 8a/8b are preferably covered attheir outlet openings by valve discs 6. Depending on the desired dampingforce setting, valve disc packets or stacks can also be used, wherebyvalve discs of various thicknesses, graduated diameters or advanceopening cross sections can preferably be set inside the packet.

The piston 3 is preferably guided or centered by a journal 9, whichjournal 9 is a component of the piston rod 2. A supporting ring 11a ispreferably supported on a shoulder 10 of the piston rod 2, and ispreferably adjacent to a series of components consisting of a valve discpacket 6, the valve body 7, a throttle disc 12 and an additionalsupporting ring 11b. Preferably, by means of a positive fit 13, thepiston 3 is fastened to the piston rod 2.

The fastening of the piston 3 to the piston rod 2 is preferably achievedby means of a bead 14. For this bead 14, a blind hole 15 is preferablyworked into the journal 9. This blind hole 15 can advantageously have anoverlap 16 with the valve body 7. During the forming process, whichforming process can preferably be forging or possibly cold-forging, anadditional axial force component is preferably applied, and acompensation of play between the valve body 7 and the journal 9 isthereby achieved by means of bearing forces in the vicinity of theoverlap 16, so that the valve body 7 is preferably fixed on all sides.

In other words, as axial force is applied by a suitable tool duringforming, the diameter 9a (see FIG. 2a) of journal 9 is preferablyexpanded so that any play between the journal 9 and the valve body 7 issubstantially decreased, or possibly eliminated. The forming tool ispreferably forced into blind hole 15, thereby expanding the walls ofjournal 9 and simultaneously forming the beads 14. Thus, the fit betweenjournal 9 and valve body 7 is preferably much tighter than the fit whichis typically achieved by a conventional nut arrangement (i.e. a nutthreaded onto journal 9). Thus, any rattles which can be caused by thecontact between journal 9 and valve body 7 can preferably besubstantially reduced or eliminated. Further, the present inventionessentially permits the valve body 7 to be centered on the journal 9more accurately, since essentially all play between valve body 7 andjournal 9 is eliminated.

Generally, during the forming process, the journal 9 will preferablyexpand substantially equally all around its circumference, therebygrasping the valve body 7 of the piston 3 preferably on all sides. Theend result is preferably a "mushroomed" shape.

The supporting rings 11a and 11b, preferably located inside and outsidethe row of axially braced components, also each preferably perform anadditional function. For example, the supporting ring 11a preferably hasa fastening surface 17 as an additional measure to secure a piston ring18, which piston ring 18 is preferably guided essentially withoutundercutting, i.e. in this case by means of two contact surfaces 19a and19b on the valve body 7. With regard to the supporting ring 11b, itshould be noted that the ring 11b preferably has a rolling contour whichcan be used to influence the damping force characteristic. In thisembodiment, the rolling contour is preferably formed by two essentiallyconical surfaces 20a/20b. As a result of this particular shapingprocess, the damping force characteristic has a progressive curve in therange of higher flow velocities.

Further, in one preferred embodiment as shown in FIG. 2a, the valve body7 may have two preferably concentric grooves 7a and 7b. The grooves 7aand 7b may preferably serve to assist in increasing the pressure forcegenerated by passage 8b, since passage 8b has a relatively smalldiameter 8c. The piston 3 may also include a spring body 6a or possiblya spring valve.

The embodiment illustrated in FIG. 3 is essentially distinguished fromthe embodiment illustrated in FIG. 2 in one aspect by the fact that thesupporting ring 11a, with its fastening surface 17, is preferably atleast partly supported on the end face of the valve body 7. Thefastening surface 17, as well as the contact surfaces 19a and 19b,preferably form a chamber for the piston ring 18.

With regard to the piston ring 18, essentially all that needs to betaken into consideration are the contact surface 19a, and the height ofthe piston ring.

As a variant of the configuration illustrated in FIG. 2, in FIG. 3 thethrottle disc 12 is preferably shifted toward the supporting ring 11a.

Thus, the overlap 16 can be preferably significantly increased whileretaining the same depth of the blind hole 15, possibly by relocatingthe throttle disc 12.

The supporting ring 11b is also preferably designed so that the decreasein pressure inside the valve occurs over a longer flow distance. Thesupporting ring 11b, together with the valve body 7, preferably forms anannular gap 21, so that unpleasant flow noises can be suppressed.

To influence the valve characteristic, a return stop 22, preferably inthe form of a spring body with a cover disc, can be used, in particularif only small volumes need to be handled in the compression direction.

Of course, it should be understood that the valve design described abovecan also be employed in a bottom valve. Such a bottom valve may includethat shown in FIG. 55 of U.S. Pat. No. 4,650,042, granted to HeinzKnecht et al. on Mar. 17, 1987, or that shown in FIG. 1 of U.S. Pat. No.4,802,561, granted to Heinz Knecht et al. on Feb. 7, 1989.

FIG. 4 and 4a illustrate two embodiments of a piston 103 in a two-tubeshock absorber. In FIG. 4, the piston 103 is illustrated in crosssection, whereby on the piston rod 102 there is a preferably cylindricalcomponent 108, which cylindrical component 108 in this embodiment isconfigured as a journal of the piston rod 102. The cylindrical component108 preferably holds, in the axial direction, the valve disc 106aand-the valve body 107. The fastening element 109 is preferably pushedonto the cylindrical component 108, and an appropriate prestress isapplied. After the application of the corresponding prestress, thefastening of the fastening element 109 preferably to the cylindricalcomponent 108 can be accomplished in the form of a weld joint, e.g. bylaser welding, in spots or alternatively over the entire circumference.The two embodiments shown in FIGS. 4 and 4a preferably illustrate anall-around weld seam 109b and a spot weld 109a, respectively. When anall-around weld seam 109b is used, the fastening element 109 canpreferably be in the form of a sleeve as shown in FIG. 4a. If, on theother hand, a spot weld 109a is used, the fastening element 109 canpreferably be in the form of a pot-shaped component as shown in FIG. 4a.

Thus, if a spot weld 109a is employed, the strength of the fasteningelement may preferably be increased by including a bottom portion 109c.Thus, the fastening element preferably has the form of a "pot".

The embodiments illustrated in FIGS. 4 and 4a show that the valve body107 and the valve discs 106a are already fastened to the cylindricalcomponent by means of a riveted joint 115. In an additional assemblystep, the valve discs 106b are preferably prestressed and fastened.

Also shown in FIGS. 4 and 4a are passages 107a and 107b, one preferablyfor each direction of flow. The piston 103, in one embodiment thereof,may also include a valve 107c, which valve may serve to regulate orcontrol the flow through passages 107a and 107b. The passages 107a and107b, as well as the valve 107c are generally well-known to those ofordinary skill in the art and will not be discussed further here.

FIG. 5 illustrates a piston 103 of a shock absorber, in which thecylindrical component 108 is preferably provided with a hole 110. Asphere can preferably serve as the expander element 111, and is insertedinto this hole 110, so that a positive fit is preferably produced bymeans of the projections 112 and recesses 113, and by the expansion ofthe cylindrical component 108 preferably as a result of the pressureexerted by the expander element 111. This spherical closure illustratedin FIG. 4 can also preferably be installed essentially without thegeneration of any chips which can typically be caused by cutting ormachining processes. By means of a corresponding device, or suitabletool, a corresponding pre-stress can be applied to the fastening element109, whereby the expander element 111, the cylindrical component 108,and the fastening element 109 can then be connected to one another inthe respective or desired position. The embodiment illustrated in FIG. 5is also preferably provided with a riveted joint 115.

Passages 107a and 107b are shown in the embodiment illustrated in FIG.5a, one passage preferably for each direction of flow. The piston 103,in one embodiment may also have a valve 107c which valve 107c can-serveto regulate the flow through passages 107a and 107b. The passages 107aand 107b and the valve 107c are generally well-known to those ofordinary skill in the art and will not be discussed further here.

FIG. 6 shows a fastening element 109 preferably made of light metal orlight metal alloy, which fastening element 109 has preferably beenshrink-fitted in an essentially contactless manner onto the cylindricalcomponent 108. The groove 116 of the cylindrical component is therebypreferably Used to achieve the positive fit.

The type of fastening illustrate in FIG. 6 may also conceivably beaccomplished by a compression fitting of fastening element 109 ontocylindrical component 108. In this type of fastening, a suitable toolcan preferably be used to grasp fastening element 109 and bycompression, force fastening element 109 onto cylindrical component 108.

As shown in FIG. 6a, one embodiment of the present invention may includethe valve body 107 having passages 107a and 107b, one preferably foreach direction of flow. The piston 103 may also include a valve 107cwhich valve 107c can preferably serve to regulate or control the flowthrough passages 107a and 107b. The passages 107a and 107b, and valve107c are well known in the art and will not be discussed further here.

FIG. 7 illustrates an additional type of connection, whereby acylindrical component 114 is preferably housed in the hole 110 of thecylindrical component 108. After the prestress has preferably beenapplied by means of the cylindrical component 114 on the valve discs106b, the fastening can be realized, for example, by means of a laserweld 117. The shoulder 118 preferably reduces the distance from theoutside to the weld point 117, or in different embodiments the shoulder118 can preferably be used to achieve a distance which is preferablyapproximately equal along the circumference of the cylindrical component108.

As shown in FIG. 7a, one embodiment of the present invention may includethe passages 107a and 107b of the valve body 107. The piston 103 mayalso include a valve 107c. The passages 107a and 107b, and valve 107care well known in the art and will not be discussed further here.

FIGS. 8a-8d illustrate one example of the sequence of an automaticassembly process. In FIG. 8a, valve discs 106a and the valve body 107are preferably threaded onto the piston rod 102, which are then (FIG.8b) preferably connected together by means of the riveted joint 115. Thevalve discs 106b are then (FIG. 8c) preferably assembled with thecylindrical element 114. After the application of a prestress (FIG. 8d),the fastening is preferably performed, e.g. by means of the weld 117.

FIG. 9 illustrates a bottom valve, in which bottom valve once again thevalve discs 106 and the valve body 107 are preferably threaded onto thecylindrical component 108, and are axially prestressed preferably bymeans of a fastening element 109 and fastened by means of a weld joint108a (see FIG. 9a). Alternatively, this weld joint 108a (see FIG. 9a)can preferably be replaced by a positive connection (not shown), inwhich the fastening element 109 and the cylindrical component 108 arepreferably connected by means of an expander element 111, similar to theone illustrated in FIG. 5, which expander element 111 is preferablyintroduced in a hole (not shown) of the cylindrical component 108. Hereagain, it is also possible to shrink fit the fastening element 109 ontocylindrical component 108, similar to the arrangement illustrated inFIG. 6.

Various types of bottom valves in which the present invention may beincorporated in a manner similar to that described with regard to FIGS.9 and 9a may be disclosed in U.S. Pat. No. 4,802,561 and U.S. Pat. No.4,650,042, both cited previously herein.

Various types of forming processes which may conceivably be utilized inaccordance with the embodiments of the present are disclosed in "MetalForming Fundamentals and Applications", by Altan et al., published bythe American Society for Metals in 1983. Pages 8 through 35 describevarious forming techniques and methods which may be used to form variouscomponents of the present invention.

Various types of forming machines and forming tools which mayconceivably be utilized to form various components of the presentinvention are also discussed in the aforementioned American Society forMetals publication on pages 103, 119, 120, 126, and 174-177. Someexamples of forming machines discussed in the these pages are screwpresses, crank presses, rolling mills, and hammers.

Further, the process of plastic deformation, which process in at leastsome aspects may apply to the forming of the various components of theembodiments of the present invention, is discussed on pages 45-82 of theaforementioned American Society for Metals publication.

The aforementioned American Society for Metals publication, namely"Metal Forming Fundamentals and Applications" the complete text thereofand the specific pages cited hereinabove, are hereby incorporated byreference as if set forth in their entirety herein.

FIGS. 10 and 11 show a typical shock absorber or vibration damper inwhich the embodiments of the present invention may conceivably beincorporated. It should be understood that the components discussedhereinbelow with reference to FIGS. 10 and 11 may essentially beconsidered to be interchangeable with the components discussedhereinabove with reference to FIGS. 1 through 9a.

FIG. 10 shows a complete shock absorber or oscillation damper 200, adetailed illustration of the valve unit 201 being omitted for the sakeof clarity. The oscillation damper 200 essentially includes a pressurepipe 202 in which a piston 203 on a piston rod 204 divides a workingspace 205 into an upper or piston-rod-side working chamber 206. A bottomvalve unit 207 closes the pressure pipe 202 at the lower end thereof. Afluid path 208 is formed between the pressure pipe 202 and anintermediate pipe 209, said intermediate pipe 209 being arrangedconcentrically with respect to the pressure pipe 202. A connectingorifice 210 in the pressure pipe 202 connects the upper working chamber211 with the fluid path 208. A compensating chamber 212 is confinedbetween the intermediate pipe 209 and a portion of the pressure pipe202, on the one hand, and the container tube 213 on the other hand. Thiscompensating chamber 212 is axially limited by a base member 214 and apiston rod guiding and sealing unit 215. The working space 205 isseparated by the piston 203 into the upper working chamber 211 and thelower working chamber 206. Both the upper and the lower working chambersare filled with a liquid. The compensating chamber 212 is also filledwith damping liquid Up to the level L, and possibly contains apressurized gas above the level L. The bottom valve unit 207 providescommunication between the working chamber 206 and the compensatingchamber 212. The piston 203 provides communication between the lowerworking chamber 206 and the upper working chamber 211. According to anillustrative example, the oscillation damper works as follows: When thepiston rod 204 moves upwards, a high flow resistance occurs across thepiston 203 and a high pressure is generated in the upper working chamber211. Liquid from the upper working chamber 211 flows through said highflow resistance into the lower working chamber 206. As the piston rod204 moves outward of the working space 205, the available volume withinthe working space 205 is increased. Therefore, liquid can flow from thecompensating chamber 212 through the bottom valve unit 207 into thelower working chamber 206. The flow resistance through the bottom valveunit 207 is small in this phase of operation. The movement of the pistonrod 204 with respect to the pressure pipe 202 is damped.

On inward movement of the piston rod 204 fluid flows from the lowerworking chamber 206 through the piston 203 into the upper workingchamber 211. The flow resistance across the piston 203 is relativelysmall and the flow resistance across the bottom valve unit 207 isrelatively large. Therefore, a considerable pressure exists even withinthe upper working chamber 211. The volume within the working space 205is reduced by the piston rod 204 entering into the working space 205.Thus, damping liquid must flow from the lower working chamber 206through the bottom valve unit 207 into the compensating chamber 212. Inthis phase of operation the flow resistance through the bottom valveunit 207 is high such that a high pressure occurs within the lowerworking chamber 206 and also within the upper working chamber 211.

By the connecting orifice 210 and the fluid path 208 the upper workingchamber 211 is connected with the compensating chamber 212 via the valveunit 201. This is shown in more detail in FIG. 11, which will bedescribed later. As long as the valve unit 201 is closed, the bypassestablished by the connecting orifice 210, the fluid path 208 and thevalve unit 201 is also closed. This is the hardest mode of operation ofthe oscillation damper. When, however, the valve unit 201 is more orless opened, the bypass is also open. As a result thereof the followingbehavior exists: On upward movement of the piston rod 204 liquid canflow from the highly pressurized upper working chamber 211 not onlyacross the piston 203 providing a high flow resistance but also from theworking chamber 211 through the bypass 210, 208, 201 to the compensatingchamber 212. Such, the damping force is reduced.

When the piston rod 204 moves downwards, there exists again a highpressure within the upper working chamber 211, as described above.Therefore, damping liquid can flow from the upper working chamber 211through the bypass 210, 208, 201 to the compensating chamber 212. Thismeans that the damping liquid which must be expelled from the workingspace 205 as a result of the reduced volume therein does not only escapethrough the bottom valve unit 207 to the compensating chamber 212 butcan also partially escape through the bypass 210, 208, 201 to thecompensating chamber 212. Such, the damping force is again reduced bythe open bypass 210, 208, 207. It is to be noted that the direction offlow of the damping liquid through the bypass 210, 208, 207 is the same,both on upward movement and downward movement of the piston rod 204 withrespect to the pressure pipe 202. By increasing the flow resistancethrough the valve unit 201 the damping force can be increased both forupward and downward movement of the piston rod 204, and by increasinglyopening the valve unit 201 the damping force can be reduced both forupward movement and downward movement of the piston rod 204. It ispossible to selectively open and close the valve unit or to continuouslyvary the flow resistance through the valve unit 201.

In FIG. 11 one can again see the fluid path 208 and the, compensatingchamber 212, which are interconnectable through the valve unit 201. Thefluid path 208 is connected to the upper working chamber 211 as shown inFIG. 10. The flow direction from the fluid path 208 to the compensatingchamber 212 across the valve unit 201 is indicated in FIG. 11 by thedotted line D provided with arrows indicating the flow direction bothfor inward movement and outward movement of the piston rod 204 withrespect to the pressure pipe 202. One can see in FIG. 11 a valve memberV Which can be lifted with respect to a valve seat S, such as to openthe flow path D from the fluid path 208 to the compensating chamber 212.

For explaining the principles of the embodiment of the present inventionshown in FIGS. 10 and 11, it is sufficient to say that the valve memberV is urged downward in the closing sense towards the valve seat S by ahelical compression spring H and that the valve member V can be liftedin response to upward movement of an electromagnetic armature member A.This armature member A is biased in downward direction by a helicalcompression spring G and can be lifted by energization of a magneticcoil 219 which is energized through a current supple cable 245.

The valve unit 201 comprises a housing 220. This housing 220 is composedby the side tube 217 and a cover unit 221. The side tube 217 is weldedat 222 to the container tube 216. The cover unit 221 is fastened to theside tube 217.

A pot-shaped valve components housing 233 is inserted into the side tube217 and Is axially located on a shoulder face 230 inside the side tube217. Various valve components are located inside the valve componentshousing 223. The lower end of the valve components housing 223 is shapedas a tube section 224, which provides the valve seat S and is sealinglyconnected to the fluid path 208.

The cover unit 221 comprises an iron jacket 225 integral with an ironend wall 226. The iron jacket 225 and the iron end wall 226 are coatedwith a plastic layer 227. The annular electromagnetic coil 219 is housedwithin the iron jacket 225. This electromagnetic coil 219 is carried bya coil carrier 228, which is annular about the axis B_(x) and is open inradial outward direction. The coil carrier 228 is closed in radiallyoutward direction by a plastics material 229 integral with the plasticlayer 227 through openings 237 of the iron jacket 225. The plasticslayer 227 and the plastics material 231 are integrally moulded byinjection moulding with the iron jacket 225, the iron end wall 226integral therewith and the electromagnetic coil 219 carrier 228 beinginserted into the injection mould.

A ferromagnetic core 232 is inserted into a central opening of the ironend wall 226 and covered by the plastics layer 227. An iron flangeportion 233 is provided at the lower side of the electromagnetic coil219 and is engaged with a shoulder face 234 of the iron jacket 225. Apole tube 235 is seated within an annular recess 236 of the iron flangeportion 233. The pole tube 235 is sealingly connected to the iron flangeportion 233 and to the ferromagnetic core 232. The armature A is guidedwithin the pole tube 235. The pole tube 235 is made of nonmagneticmaterial so that the magnetic field lines are deflected by the lower endof the pole tube 235. The iron jacket 225, the iron end wall 226, theferromagnetic core 232 and the iron flange portion 233 form aferromagnetic core arrangement which toroidally surrounds theelectromagnetic coil 219.

The cover unit 221 is fastened to the side tube 217 by a sleeve-shapedextension 238 of the iron jacket 225. This sleeve-shaped extension 238axially overlaps the side tube 217 by a circumferential bead 239 beingembossed into a circumferential groove 240 on the radially outer face ofthe side tube 217. The iron jacket 225 is provided with a pretensioningflange 241. The pretensioning flange 241 offers a pretension face 242.The cover unit 221 can be pretensioned in downward direction as shown inFIG. 11 toward the container tube 216 by a pretensioning tool engagingthe container tube 216, on the one hand, and the pretensioning face 242,on the other hand. Such, the iron flange portion 233 is pressed againstthe upper end of the valve components housing 223, the valve componentshousing 223 is engaged with the shoulder face 230 of the side tube 217,and the iron flange portion 233 is engaged with the shoulder face 234 ofthe iron jacket 225. The helical compression spring H is compressedbetween the iron flange portion 233 and the valve member V, which isseated on the valve seat S.

While maintaining this pretension of the cover unit 221 against the sidetube 217, the bead 239 is rolled or caulked into the circumferentialgroove 240 of the side tube 217 so that after removing the pretensioningtool an internal pretension is maintained. A sealing ring 243 is,therefore, maintained in sealing engagement with the valve componentshousing 223, the iron flange portion 233 and the side tube 217. Such,the compartment C confined by the side tube 217 and the cover unit 221is sealed against atmosphere. All components of the valve unit 201 arepositioned with respect to each other, and the helical compressionspring H as well as the helical compression spring G and further springsare biased to the desired degree.

It is to be noted that the upper end of the side tube 217 is radiallyengaged at 244 with the iron flange portion 233 such that when rollingor caulking the bead 239 into the groove 240, no deformation of the sidetube 217 and of the iron jacket 225 can occur.

The electromagnetic coil 219 is completely separated from the liquidwithin the compartment C by the iron flange portion 233. The pretensionduring connecting the cover unit 221 and the side tube 217 is selectedsuch that no play can occur.

One feature of the invention resides broadly in the valve for ahydraulic telescoping strut shock absorber, in which, running through avalve body, there are passages whose outlet-side openings are covered byring-shaped valve discs, whereby the valve discs and the valve body arefastened and axially braced in line on a journal, characterized by thefact that at least some of the valve discs 6, 106 and the valve body 7,107 are non-detachably fastened on the journal 9, 109.

Another feature of the invention resides broadly in the valvecharacterized by the fact that the fastening is a positive fit and/or aweld joint.

Yet another feature of the invention resides broadly in the valvecharacterized by the fact that the positive fit 13 is formed by thejournal 9.

Still another feature of the invention resides broadly in the valvecharacterized by the fact that the journal 9 has a blind hole 15, sothat a ring wall is formed which has an overhang in relation to thevalve discs 6 and valve body 7 threaded over it, whereby the overhangforms the positive fit 13 by means of a riveted joint 14.

A further feature of the invention resides broadly in the valvecharacterized by the fact that there is an overlap 16 between the blindhole 15 and the valve body 7.

Another feature of the invention resides broadly in the valvecharacterized by the fact that inside the components axially braced inline, there is at least one supporting ring 11a/11b for the valve discs6.

Yet another feature of the invention resides broadly in the valvecharacterized by the fact that the supporting ring 11b has a definedrolling contour.

Still another feature of the invention resides broadly in the valvecharacterized by the fact that the rolling contour is formed by twoconnected conical surfaces 20a/20b.

A further feature of the invention resides broadly in the valvecharacterized by the fact that it is realized in the form of a pistonvalve, in which a piston ring 18 is fastened with no undercutting on thevalve body 7.

Another feature of the invention resides broadly in the valvecharacterized by the fact that the supporting ring 11a has a fasteningsurface 17 for the piston ring 18.

Yet another feature of the invention resides broadly in the valvecharacterized by the fact that the supporting ring 11a with itsfastening surface 17 is partly supported on the end face of the valvebody 7.

Still another feature of the invention resides broadly in the valvecharacterized by the fact that at least some of the valve discs 106 andthe valve body 107 are threaded and braced onto a cylindrical component108 and that,a fastening element 109 is fastened to the cylindricalcomponent 108.

A further feature of the invention resides broadly in the valvecharacterized by the fact that the valve discs 106 facing the piston rod102 and the valve body 107 are fixed axially.

Another feature of the invention resides broadly in the valvecharacterized by the fact that the cylindrical component 108 is acomponent of the piston rod 102.

Yet another feature of the invention resides broadly in the valvecharacterized by the fact that the cylindrical component 108 has a hole110 in which a cylindrical component 114 provided with the valve discs106 is fixed.

Still another feature of the invention resides broadly in the valvecharacterized by the fact that the cylindrical component 108 issurrounded by the fastening element 109 and the cylindrical component108 is expanded from inside to outside.

A further feature of the invention resides broadly in the valvecharacterized by the fact that the expansion of the cylindricalcomponent 108 is accomplished by means of an expander element ill housedin a hole 110 of the cylindrical component 108.

Another feature of the invention resides broadly in the valvecharacterized by the fact that the expander element 111 is a sphere.

Yet another feature of the invention resides broadly in the valvecharacterized by the fact that the cylindrical component 108 and/or thefastening element 109 is/are provided on the surfaces facing one anotherwith at least one projection 112 and/or one recess 113.

Still another feature of the invention resides broadly in the valvecharacterized by the fact that the projection 112 and/or the recess 113run in an annular fashion over the entire circumference.

A further feature of the invention resides broadly in the valvecharacterized by the fact that the fastening element 109 is made oflight metal or a light metal alloy and is shrink-fitted on thecylindrical component 108 in a contactless manner by electrically pulsedmagnetic fields.

Examples of shock absorber assemblies and components associatedtherewith, which may be utilized in accordance with the embodiments ofthe present invention, may be found in the following U.S. Pat. Nos.4,986,393, which issued to Preukschat et al. on Jan. 22, 1991;4,749,070, which issued to Moser et al. on Jun. 7, 1988; and 4,723,640,which issued to Beck on Feb. 9, 1988.

All of the patents, patent applications and publications recited herein,and in the Declaration attached hereto, are hereby incorporated byreference as if set forth in their entirety herein.

Federal Republic of Germany Patent Application Nos. P 43 15 457.3, filedon May 10, 1993, and P 43 15 458.1, filed on May 10, 1993, havinginventors Andreas Forster, Andreas Sieber, Wolfgang Schuhmacher andHubert Beck, and DE-OS P 43 15 457.3 and P 43 15 458.1 and DE-PS P 43 15457.3 and P 43 15 458.1, are hereby incorporated by reference as if setforth in their entirety herein.

The invention as described hereinabove in the context of the preferredembodiments is not to be taken as limited to all of the provided detailsthereof, since modifications and variations thereof may be made withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A shock absorber for a motor vehicle, said shockabsorber comprising:a cylinder defining a chamber therein, said cylindercontaining a damping fluid; a piston rod sealingly projecting into saidcylinder and being axially displaceable within said said cylinder; apiston attached to said piston rod, said piston being slidably disposedwithin said cylinder to sealingly divide said chamber into first andsecond chambers; means for permitting fluid communication between saidfirst chamber and said second chamber; a first end and a second end;said cylinder being disposed between said first end and said second end;said first end comprising first means for connecting said shock absorberto a first body; said second end comprising second means for connectingsaid shock absorber to a second body; said piston rod comprising acylindrical protrusion; means for fastening said cylindrical protrusionand said piston together; said fastening means comprising a portion,said portion comprising means for being destroyed during the removal ofsaid cylindrical protrusion from said piston, said means for beingdestroyed being the portion within said fastening means for holding saidcylindrical protrusion and said piston together, whereby saidcylindrical protrusion and said piston are substantially non-detachablefrom one another, said cylindrical protrusion and said piston beingdetachable from one another only upon substantial destruction of saidmeans for being destroyed; said means for being destroyed comprises asubstantial portion of said fastening means; said means for beingdestroyed comprises at least one weld; said fastening means furthercomprises a cylindrical sleeve disposed about said cylindricalprotrusion; said cylindrical sleeve comprises a first end and a secondend, said second end being disposed adjacent said piston and said firstend being disposed a substantial distance from said first end; saidcylindrical protrusion and said cylindrical sleeve are fastened to oneanother by said at least one weld; said cylindrical sleeve comprises atleast one of a) and b):a) an opening disposed at said first end of saidcylindrical sleeve; and b) a bottom portion disposed at said first end,said bottom portion substantially enclosing said cylindrical protrusionwithin said cylindrical sleeve; said piston comprises valve meansdisposed about said cylindrical protrusion; said valve means comprisesdisc means for regulating fluid flow in said means for permitting fluidcommunication;. said piston further comprises a piston body; saidfastening means axially fastens said valve means against said pistonbody and said fastening means axially fixes said piston body on saidcylindrical protrusion; said fastening means fastens said cylindricalprotrusion and said piston together such that at least one of: a portionof said cylindrical protrusion and a portion of said piston is destroyedupon the removal of said cylindrical protrusion from said piston; saidmeans for permitting fluid communication comprises:a first passage and asecond passage; said disc means comprises:a first disc packet and asecond disc packet; said first disc packet and said second disc packeteach having at least one disc; said first passage comprises a firstopening and a second opening; said second passage comprises a thirdopening and a fourth opening; said first disc packet is disposedadjacent said first opening of said first passage and said third openingof said second passage; and said second disc packet is disposed adjacentsaid second opening of said first passage and said fourth opening ofsaid second passage.
 2. A method of making a shock absorber for a motorvehicle, the shock absorber comprising: a cylinder defining a chambertherein, the cylinder containing a damping fluid; a piston rod sealinglyprojecting into the cylinder and being axially displaceable within thecylinder; a piston attached to the piston rod, the piston being slidablydisposed within the cylinder to sealingly divide the chamber into firstand second chambers; means for permitting fluid communication betweenthe first chamber and the second chamber; a first end and a second end;the cylinder being disposed between the first end and the second end;the first end comprising first means for connecting the shock absorberto a first body; the second end comprising second means for connectingthe shock absorber to a second body; the piston rod comprising acylindrical protrusion; means for fastening the cylindrical protrusionand the piston together; the fastening means comprising a portion; saidportion comprising means for being destroyed during the removal of thecylindrical protrusion from the piston, the means for being destroyedbeing the portion of the fastening means for holding the cylindricalprotrusion and the piston together, whereby the cylindrical protrusionand the piston are substantially non-detachable from one another, thecylindrical protrusion and the piston being detachable from one anotheronly upon substantial destruction of the means for being destroyed; saidmethod comprising the steps of:providing the cylinder, the cylinderdefining a chamber therein, the cylinder containing a damping fluid;providing the piston rod, the piston rod sealingly projecting into thecylinder and being axially displaceable within the cylinder; providingthe piston, the piston being attached to the piston rod, said pistonbeing slidably disposed within the cylinder to sealingly divide thechamber into first and second chambers; providing the means forpermitting fluid communication between the first chamber and the secondchamber; providing the first end and the second end, the cylinder beingdisposed between the first end and the second end; said providing of thefirst end comprising:providing the first means for connecting the shockabsorber to a first body; said providing of the second endcomprising:providing the second means for connecting the shock absorberto a second body; said providing of the piston rod comprising:providingthe cylindrical protrusion; said method further comprising the stepsof:forming the means for fastening the cylindrical protrusion and thepiston together; said step of forming the fastening meanscomprises:forming the means for being destroyed during the removal ofthe cylindrical protrusion from the piston, the means for beingdestroyed being formed for holding the cylindrical protrusion and thepiston together, whereby the cylindrical protrusion and the piston aresubstantially non-detachable from one another, the cylindricalprotrusion and the piston being detachable from one another only uponsubstantial destruction of the means for being destroyed; said step offorming the means for being destroyed further comprises:forming themeans for being destroyed on a substantial portion of the fasteningmeans; providing at least one weld; said providing of the fasteningmeans comprises:providing a cylindrical sleeve disposed about thecylindrical protrusion; said providing of the cylindrical sleevecomprises:providing a first end and a second end, the second end beingdisposed adjacent the piston and the first end being disposed asubstantial distance from the second end; fastening the cylindricalprotrusion and the cylindrical sleeve to one another with the at leastone weld; said providing of the cylindrical sleeve comprises at leastone of a) and b):a) providing an opening disposed at the first end ofthe cylindrical sleeve; and b) providing a bottom portion disposed atthe first end, the bottom portion substantially enclosing thecylindrical protrusion within the cylindrical sleeve; said providing ofthe piston comprises:providing valve means; disposing the valve meansabout the cylindrical protrusion; said providing of the valve meanscomprises:providing disc means; regulating fluid flow in the means forpermitting fluid communication by means of the disc means; saidproviding of the piston comprises:providing a piston body; axiallyfastening the valve means against the piston body by means of thefastening means; axially fixing the piston body on the cylindricalprotrusion by means of the fastening means; said step of forming thefastening means further comprises fastening said cylindrical protrusionand said piston together such that at least one of: a portion of saidcylindrical protrusion and a portion of said piston is destroyed uponthe removal of said cylindrical protrusion from said piston; saidproviding of the means for permitting fluid communication furthercomprises:providing a first passage and a second passage; said providingof the disc means further comprises:providing a first disc packet and asecond disc packet, said first disc packet and said second disc packeteach having at least one disc; said providing of the first passagefurther comprises providing a first opening and a second opening; saidproviding of the second passage further comprises providing a thirdopening and a fourth opening; said method further comprising:disposingsaid first disc packet adjacent said first opening of said first passageand said third opening of said second passage; and disposing said seconddisc packet adjacent said second opening of said first passage and saidfourth opening of said second passage.